What you need to know: I . The cell is the basic unit of life:
As we have already discussed....The discovery of the cell was made possible by the invention of the microscope (1600s) As microscopes improved, scientists observed that all living organisms were made up of cells, leading eventually to the development of the Cell Theory Cell TheoryAll organisms contain one or more cells which are capable of carrying on the life activities needed by the organism. This idea is often referred to as the cell theory.
Parts of the Cell Theory
The cell is the unit of structure in all living things.
The cell is the unit of function in all living things.
All cells come from preexisting cells.
What defines a cell? A cell
1. Is the lowest level of structure capable of performing all 5 activities of life
2. Is bounded by a plasma membrane "envelope"
3. Contains cytoplasm, DNA, enzymes, organelles
II. How big are cells?
Our eyes can see things as small as ~0.1 mm. There are a few cells that can be seen without the aid of a microscope, but, a general rule is that most eukaryotic cells are ~ 0.05 mm (50 microns) to 0.005 mm (5 microns) long, bacterial cells are much smaller (~ 3 microns or less). Viruses are even smaller (nano-meters!)
IV. What types of cells are there? Prokaryotic vs. Eukaryotic. 1. Features of Prokaryotic ("pre-nucleus") cells: Few internal parts: bacteria and blue-green algae (Kingdoms Archaebacteria and Eubacteria)
1. Very small (typically less that 5 microns)2. Lack internal compartments and organelles3. Lack a nucleus - DNA is not separated from the cytoplasm4. One circular chromosome5. Tough external walls
2. Features of Eukaryotic ('true-nucleus") cells: (Kingdoms: protists, plants, fungi and animals) Numerous internal structures. See p 57 for details and labels to all structures.
1. Subdivided by internal membranes into different compartments 2. DNA is enclosed by a membrane-bound nucleus3. DNA organized into chromosomes 4. Cytoplasm surrounds the nucleus and organelles5. Plant cells, yeast cells, and protists have a tough cell wall, animal cells do not.
A typical animal cell
A typical plant cell
V. Cellular Compartments and Organelles: What is inside (and surrounds the outside) of cells?
1. Plasma Membrane: All cells are surrounded by a plasma membrane! The plasma membraneis a phospholipid bilayer studded with proteins. Lipids have a hydrophilic head and a hydrophobic tails that, in water, spontaneously form into a bilayer.
Function of the lipids: Keeps the inside in and outside out! Materials enter and exit the membrane through diffusion, osmosis, or membrane transport proteins or recognition proteins.
This picture (left) just shows the lipids, but that's only part of the story...A cutaway view of the plasma membrane illustrating the Fluid-mosaic model of plasma membrane structure is shown on the right:
2. Cytoplasm semifluid "soup" of proteins, enzymes, dissolved salts, sugars. All the organelles and the nucleus float in the cytoplasm...
3. Nucleus contains chromatin: a combination of DNA (genes) and associated proteins, floating in a liquid nucleoplasm, surrounded by nuclear envelope (another lipid bilayer). The nucleolus is an area where synthesis of ribosomal genes rRNA) takes place
4. The EndoMembrane (or CytoMembrane) System (see figure above):
A. Ribosomes small structures in the cytoplasm made of RNA and protein that assemble protein chains. Can be "free" in the cytoplasm or bound to the ER
B. Rough Endoplasmic Reticulum (rough ER) sorts and modifies protein chains delivered by bound ribosomes
C. Smooth Endoplasmic Reticulum (smooth ER) lacks ribosomes. Site of lipid (membrane) synthesis
D. Golgi Body connects with the smooth ER, completes lipid synthesis and sorts proteins to their correct destination in small vesicles
E. Vesicles transport proteins and lipids to the cell surface; bring proteins and lipids into cell from the cell surface, digest compounds (in lysosomes)
F. Lysosomes: intracellular digestion - contain a potent brew of digestive enzymes
G. Peroxisomes: break down fatty acids, amino acids, and alcohol
5. Mitochondria: A double membrane-bound organelle that makes ATP for cellular energy (not just one lipid bilayer, but TWO). Contains its own genome!
6. Chloroplast:(Plants only) A double membrane-bound organelle that makes sugar from sunlight and CO2during photosynthesis (not just one lipid bilayer, but TWO). Contains its own genome!
7. Cytoskeleton (microtubles and microfilaments) provide cell shape, internal "skeleton" and cell movement.
8. Centioles made of microtubules, may assist in cell division.
9. Cell Wall (Plant, Protists, and Fungi): A tough, rigid (but somewhat elastic) structure made up of cellulose (plants) chitin (fungi) a variety of proteins (protists).
VI. Way cool cells: The "typical" cell is usually shown as a ball, or a box, but REAL cells come in all kinds of shapes and sizes! However, inside each of these cells is all the same components as the typical cells above (exception: mature blood cells - which live for only a short time - lose their nucleus because they are essentially finished with any new protein synthesis, but the cells below have generally all of the components above.)
Human Nerve cell
Human Red Blood Cells
Human sperm cell
Pseudomonas, a bacteium associated with lung infections [Image]
Diatoms, 1-celled protists with glass shells (Starr)
For a look at some more "way cool" cells, check out the Cells Alive webpage.
Cell Organelle
Function
nucleus
control center of the cell
contains DNA which directs the synthesis of proteins by the cell
mitochondrion
carries on the process of cell respiration converting glucose to ATP energy the cell can use
endoplasmic reticulum
transport channels within the cell
ribosome
found on the endoplasmic reticulum and free within the cell
responsible for the synthesis of proteins for the cell
cell membrane
selectively regulates the materials moving to and from the cell
food vacuole
stores and digests food
contractile vacuole
pumps out wastes and excess water from the cell
chloroplast
found in plant cells and algae
carries on the process of photosynthesis
cell wall
surrounds and supports plant cells
Membrane ProcessesThe processes of diffusion and active transport are important in the movement of materials in and out of cells. |||| Diffusion
||
Diffusion or passive transport is the movement of materials from a region of higher to a region of lower substance concentration. The diagram at the right shows the movement of molecules from higher concentration on side A to a lower concentration on side B.
|||| Active Transport
||
In active transport, molecules move from a region of lower concentration to a region of higher concentration. As this process does not naturally occur, the cell has to use energy in the form of ATP to make active transport occur.
CELL STRUCTURE & FUNCTION
4. Describe similarities and differences of cell organelles, using diagrams and tables.
- Identify cell structures including cell membrane, cell wall, nucleus, ribosomes, smooth endoplasmic reticulum, rough endoplasmic reticulum, Golgi body, vacuole, chloroplast, and mitochondria.
- Identify scientists who contributed to the cell theory
Examples: Hooke, Schleiden, Schwann, Virchow, van Leeuwenhoek- Distinguishing between prokaryotic and eukaryotic cells
- Identifying various technologies used to observe cells
Examples: light microscope, scanning electron microscope, transmission electron microscopeCells Alive.... so Exactly How Big Really is it...?
http://www.cellsalive.com/howbig.htm
Cell Structure and Function Lecture Notes
Study Guides
Anatomy of Plant and Animal Cells- Name these organelles!
Take practice tests with this Study Guide for Ch 2 and 3
Play with this Interactive Plant and Animal Cell like the one we study in class!
projects/Activities/other class handouts
Virtual Cell Website: http://www.ibiblio.org/virtualcell/tour/cell/cell.htm
Play Who Wants to Be a Cell Millionare Game!
Concepts in Action!
http://www.youtube.com/watch?v=sa563MdIiXE&feature=grec_index&safety_mode=true&persist_safety_mode=1&safe=active
Inner Life of a Cell- Incredible!
Nobel Prize 2001 Winners- Discovery of the Cell Cycle!
Check out the ceremony! http://nobelprize.org/nobel_prizes/medicine/laureates/2001/presentation-speech.html
What you need to know:
I . The cell is the basic unit of life:
As we have already discussed....The discovery of the cell was made possible by the invention of the microscope (1600s) As microscopes improved, scientists observed that all living organisms were made up of cells, leading eventually to the development of the Cell Theory
Cell TheoryAll organisms contain one or more cells which are capable of carrying on the life activities needed by the organism. This idea is often referred to as the cell theory.
What defines a cell? A cell
- 1. Is the lowest level of structure capable of performing all 5 activities of life
- 2. Is bounded by a plasma membrane "envelope"
- 3. Contains cytoplasm, DNA, enzymes, organelles
II. How big are cells?
Our eyes can see things as small as ~0.1 mm. There are a few cells that can be seen without the aid of a microscope, but, a general rule is that most eukaryotic cells are ~ 0.05 mm (50 microns) to 0.005 mm (5 microns) long, bacterial cells are much smaller (~ 3 microns or less). Viruses are even smaller (nano-meters!)- Check out **How Big are They**?
III. What do cells do?IV. What types of cells are there? Prokaryotic vs. Eukaryotic.
1. Features of Prokaryotic ("pre-nucleus") cells: Few internal parts: bacteria and blue-green algae (Kingdoms Archaebacteria and Eubacteria)
V. Cellular Compartments and Organelles: What is inside (and surrounds the outside) of cells?
VI. Way cool cells: The "typical" cell is usually shown as a ball, or a box, but REAL cells come in all kinds of shapes and sizes! However, inside each of these cells is all the same components as the typical cells above (exception: mature blood cells - which live for only a short time - lose their nucleus because they are essentially finished with any new protein synthesis, but the cells below have generally all of the components above.)
Human sperm cell
Pseudomonas, a bacteium associated with lung infections [Image]
contains DNA which directs the synthesis of proteins by the cell
responsible for the synthesis of proteins for the cell
carries on the process of photosynthesis
Membrane ProcessesThe processes of diffusion and active transport are important in the movement of materials in and out of cells.
|||| Diffusion
||
|||| Active Transport
||